Many processes for synthesizing organometallic compounds of alkali metals such as lithium, sodium and potassium have been developed so far, and there are known, for example,
synthesis of butyllithium by the reaction of butyl bromide with metallic lithium (reaction (I), non-patent document 1):C4H9Br+2Li→C4H9Li+LiBr   (I), and
synthesis of benzyllithium by the reaction of tribenzylchlorostannane with methyllithium (reaction (II), non-patent document 1):(C6H5CH2)3SnCl+4CH3Li→3C6H5CH2Li+(CH3)4Sn+LiCl   (II).
Most of the alkali metal compounds synthesized as above can produce novel organometallic reaction agents by the reaction of them with organic compounds having active proton, and therefore, they have been used for various purposes. For example, there can be mentioned production of a so-called metallocene compound using a cyclopentadienyl group as a ligand, which is well known as an organic transition metal compound, particularly an olefin polymerization catalyst. Since the metallocene compound has features that its polymerization activity is extremely high and a polymer having a narrow molecular weight distribution is obtained, studies of various synthetic processes have been made so far. Of these, a great number of processes wherein a ligand having an active proton is deprotonated by such an alkali metal compound as mentioned above and further allowed to react with a metal halide or the like have been particularly reported (patent documents 1 to 3).
In such syntheses of metallocene compounds, it has been frequently observed that deprotonation by the alkali metal compound does not proceed depending upon the structure of the ligand, and in such cases, the intended deprotonation of the ligand is promoted by using a coordination solvent such as tetrahydrofuran (THF) or by adding N,N, N′,N′-tetramethylethylenediamime (TMEDA) as a chelating agent for the purpose of enhancing basicity of the alkali metal reagent (patent document 4, non-patent document 2).
However, it is known that amines such as TMEDA and THF have problems such as evil influence on the subsequent step and remaining of them in the end product, and for example, in the production of a metallocene compound, instability of the resulting metallocene compound and lowering of activity in the polymerization reaction have been reported (patent documents 5 and 6). Further, in such compounds, there are compounds having strong toxicity and compounds having carcinogenesis, so that development of lowly hazardous substitute compounds has been promoted.
Moreover, it has been reported that a mixture of alkyllithium and potassium alkoxide exhibits extremely strong basicity (non-patent document 3).
The organopotassium compound produced by this process, however, is very sensitive to air and moisture. It is known that lithium alkoxide formed as a by-product becomes a cause of side reaction when it remains in the subsequent step. For example, in the production of a metallocene compound, the lithium alkoxide causes lowering of yield due to side reaction with a transition metal compound that is a raw material or causes marked decrease of polymerization activity due to incorporation into the resulting metallocene compound. On that account, after treatments of many steps, such as solvent cleaning and extraction, become necessary.
Accordingly, development of processes for preparing an organic alkali metal compound and an organic transition metal compound such as a metallocene compound without causing such problems has been desired.                Patent document 1: Japanese Patent No. 3,176,092        Patent document 2: Japanese Patent Laid-Open Publication No. 12290/1999        Patent document 3: Japanese Patent No. 3,320,619        Patent document 4: Japanese Patent Laid-Open Publication No. 208733/1996        Patent document 5: Japanese Patent No. 3,713,405        Patent document 6: Japanese Patent Laid-Open Publication No. 11087/2001        Non-patent document 1: the Chemical Society of Japan, Ed., “Yuki Kinzoku Kagaku (Organometallic Chemistry) (Shin Jikken Kagaku Koza (Lectures of New Experimental Chemistry) 12)”, Maruzen (1975)        Non-patent document 2: Organometallics, 2007, 26, 417-424        Non-patent document 3: Pure & Appl. Chem., 1988, 60, 1627-1634        